Efficiency of quantum dot solar cell enhanced by improving quantum dots performance

We propose an innovative description to provide a quantitative basis to enhance the conversion efficiency of InAs/GaAs quantum dot solar cells (QDSC). A theoretical approach and numerical simulation are used to improve the performance of the quantum dots and analyze the relevance to enhance the conversion efficiency. The absorption coefficient of QDs is determined in terms of dot material, dot size, size dispersion, and shape, which are used to obtain a better match between the absorption spectrum of QDs with the portion of the solar spectrum. Either increasing the surface density for raising the photocurrent or enlarging the dot size for matching well the solar spectrum is a trade-off issue. The influence of surface density, spacer thickness, and number of dot layers on the opencircuit voltage and efficiency is discussed in detail. Moreover, volume fraction can be taken as a balance reference for the counteracting effect between J_SC and V_OC.